Modern construction practices assemble wall and ceiling surfaces by using manufactured panels that are placed adjacent to one another and affixed to the structural “studs” of the building. These manufactured panels, generally referred to as “drywall,” are available from several manufactures in stock sizes. Drywall panels are configured as a filler/structural material sandwiched between two outer surface layers of paper. The structural integrity of the drywall panel relies on the bond between this paper and the internal filler material.
The drywall panels are typically attached to the building studs with drywall screws. Drywall screws typically have a tapered countersink head with a flat face. The drywall screw is installed through the drywall panel and into the stud of the building. The drywall screw is installed in the drywall so that the head of the screw is at least below the outer surface of the drywall. In this manner, the drywall panel can be coated with joint compound, drywall mud, etc. to aesthetically finish the drywall without the screw head protruding therefrom.
The drywall panel is secured to the stud by the interference of the screw head pulling the panel against the underlying stud. If the installer uses too much pressure and sets the drywall screw head too deep into the drywall panel, the outer paper layers and underlying filler layers can be damaged. Thus, it is important that the drywall screws be installed within the panel at a proper depth.
To install the drywall screws at a proper depth, there are several commercially available options for installers. There are task specific power tools, such as drywall electric screw guns or drywall screwdrivers, which have adjustable depth and clutching features to set the drywall screw at a desired depth within the drywall panel. The draw back is that these power tools are only useful for this particular job. The cost and limited use of these tools makes them impractical for users who are not professional drywall installers.
There are also simple driver bits that can be used with a standard hand drill.
These are typically referred to as “depth setter bits,” “screw indenters,” “dimpler bits,” etc (hereinafter collectively referred to as “depth setter bits”). An example of a prior art depth setter bit is shown in FIG. 4. Depth setter bits are a permanent assembly of two components. Specifically, depth setter bits include a ring R that is permanently affixed to an insert bit B (such as a one inch, Phillips bit) at a preset position. The ring R acts as a depth stop for the bit B when the bit is driving a screw within a drywall panel. More specifically, with the ring R engaging the drywall panel, further driving action by the installer results in the bit tip disengaging the screw head as the screw is driven to its finished depth in the drywall.
The prior art depth setter bit is a simple and effective installation tool, but it has some inherent drawbacks. The stop ring R makes the bit B more expensive and limits its use to the specific task of installing drywall panels. It is known in the art that the stop limit and disengagement caused by the ring R accelerates wear to the bit driver tip and therefore requires frequent replacement. Since these specialty depth setter bits are more expensive and harder to obtain than standard drive bits, the cost often outweighs the benefits of using a depth setter bit.
In addition, with the ring R being permanently attached to the bit B, the depth setter bit cannot be used in edge or corner installations. More specifically, the drive bit tip cannot sufficiently extend into the drywall panel due to the interference of the stop ring R with the drywall corner. In these situations, the ring R can cause the bit B to disengage the screw head prematurely, thereby leaving the screw head exposed above the drywall surface. In order to properly install the drywall screws in a corner, the entire depth setter bit must be removed from the chuck or receptacle of the hand tool and replaced with a standard bit, which is time consuming and inefficient.
Furthermore, the ring R and bit B combinations are used in conjunction with industry standard magnetic bit holders H that add length to the bit B for ease of use. The magnetic bit holders H have receptacles that magnetically retain the end of the bit B therein. The bit holders H also increase the magnetism of the bit B to help hold the driven screw in place on the bit end during installation. The depth setter bit rings R are generally produced from steel so that they may be press fit onto the bit B. The magnetic properties of these steel rings R diminish the magnetic force of the bit holder H and the bit B. In most bit holders H, magnetic force is typically all that is used to secure the bit within the holder. If the tip of the bit B sticks in the screw head, the pulling force being exerted on the bit B can easily overpower the holding force of the magnet, and the bit B can become dislodged from the bit holder H.
Based on the foregoing, it can be appreciated that a low-cost depth setter bit having improved magnetic properties and versatility is desired.